During an end-on collision of a vehicle, such as a full or partial frontal head-on or rear end collision, it is very important to absorb a great portion of impact energy by controlled deformation of the side members which form part of the front or rear compartments, (e.g. the engine room and trunk). It is ideal to deform, under compression, the side members in a collapsible manner because this form of deformation tends to maximize the amount of impact energy absorption.
Currently, the most popular measure is to provide a path of transmission of stress or force to structural members of the passenger compartment floor such as the side sills which extend along either side thereof. To improve the force transmission characteristics it is advantageous to increase the rigidity and stiffness of the floor. The use of extruded parts to increase stiffness and rigidity is known from JP-A-9-99870.
However, if there is a vertical offset between the floor and the side members, it is necessary to provide a joint structure whereby each front side member is rigidly connected to the floor. This establishes a structure which generates, during a collision, a moment of force which consists of the force applied to the floor by the front side member during initial stage of process of impact energy absorption, and the perpendicular distance (viz., the arm of the moment) between a point in the joint structure wherein bucking initiates and the side member. Occurrence of such moment places a bias a dash panel and its associated structure which tends to move it undesirably toward and/or into a passenger compartment which is located above the floor.
Accordingly, a need exists to minimize this bias and to ensure that vehicle structural members do not distort excessively and/or encroach into passenger cabin space in a manner which reduces passenger safety.